The present invention relates to distinguishing image pixels that relate to a background from image pixels that relate to a foreground object. It finds particular application in conjunction with identifying changes to an area monitored by a video camera and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
Visually monitoring an area for changes over time is desirable in some situations since such visual changes may indicate an investigation of the area is warranted. For example, a person suddenly appearing in a scene of an empty warehouse corridor may indicate a theft is imminent. Similarly, a change in a scene of a tank containing a fluid may indicate a leak has occurred.
Some methods used for recognizing changes in a monitored area identify the monitored area as a background and any changes to the monitored area (e.g., a person entering the empty warehouse corridor or fluid leaking from a tank) as a foreground object. One conventional method for recognizing changes in a monitored area involves first learning the background based on a sequence of images. The background is then subtracted from a future image, which results in an image including the foreground object. Some issues arise when implementing conventional background subtraction algorithms. For example, the background may not be correctly learned and/or updated, the foreground object may not be correctly determined, a pixel may be erroneously labelled as foreground, and significant changes in a pixel's exposure may cause pixels to be incorrectly labeled as foreground.
The present invention provides a new and improved apparatus and method which addresses the above-referenced problems.